From: Gao Feng <f...@ikuai8.com>
Define one new macro TCP_MAX_WSCALE instead of literal number '14',
and use U16_MAX instead of 65535 as the max value of TCP window.
There is another minor change, use rounddown(space, mss) instead of
(space / mss) * mss;
Signed-off-by: Gao Feng <f...@ikuai8.com>
---
v2: Correct the literal 14 in comment and log too, per Neal
v1: initial version
include/net/tcp.h | 3 +++
net/ipv4/tcp.c | 2 +-
net/ipv4/tcp_input.c | 9 +++++----
net/ipv4/tcp_output.c | 12 +++++-------
4 files changed, 14 insertions(+), 12 deletions(-)
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 582e377..cc6ae0a 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -78,6 +78,9 @@
/* Maximal number of ACKs sent quickly to accelerate slow-start. */
#define TCP_MAX_QUICKACKS 16U
+/* Maximal number of window scale according to RFC1323 */
+#define TCP_MAX_WSCALE 14U
+
/* urg_data states */
#define TCP_URG_VALID 0x0100
#define TCP_URG_NOTYET 0x0200
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 1665948..94f0b5b 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -2393,7 +2393,7 @@ static int tcp_repair_options_est(struct tcp_sock *tp,
u16 snd_wscale = opt.opt_val & 0xFFFF;
u16 rcv_wscale = opt.opt_val >> 16;
- if (snd_wscale > 14 || rcv_wscale > 14)
+ if (snd_wscale > TCP_MAX_WSCALE || rcv_wscale >
TCP_MAX_WSCALE)
return -EFBIG;
tp->rx_opt.snd_wscale = snd_wscale;
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index a75c48f..ed6606c 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -3759,11 +3759,12 @@ void tcp_parse_options(const struct sk_buff *skb,
!estab && sysctl_tcp_window_scaling) {
__u8 snd_wscale = *(__u8 *)ptr;
opt_rx->wscale_ok = 1;
- if (snd_wscale > 14) {
- net_info_ratelimited("%s:
Illegal window scaling value %d >14 received\n",
+ if (snd_wscale > TCP_MAX_WSCALE) {
+ net_info_ratelimited("%s:
Illegal window scaling value %d > %u received\n",
__func__,
-
snd_wscale);
- snd_wscale = 14;
+ snd_wscale,
+
TCP_MAX_WSCALE);
+ snd_wscale = TCP_MAX_WSCALE;
}
opt_rx->snd_wscale = snd_wscale;
}
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 1397194..0e807a8 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -212,12 +212,12 @@ void tcp_select_initial_window(int __space, __u32 mss,
/* If no clamp set the clamp to the max possible scaled window */
if (*window_clamp == 0)
- (*window_clamp) = (65535 << 14);
+ (*window_clamp) = (U16_MAX << TCP_MAX_WSCALE);
space = min(*window_clamp, space);
/* Quantize space offering to a multiple of mss if possible. */
if (space > mss)
- space = (space / mss) * mss;
+ space = rounddown(space, mss);
/* NOTE: offering an initial window larger than 32767
* will break some buggy TCP stacks. If the admin tells us
@@ -234,13 +234,11 @@ void tcp_select_initial_window(int __space, __u32 mss,
(*rcv_wscale) = 0;
if (wscale_ok) {
- /* Set window scaling on max possible window
- * See RFC1323 for an explanation of the limit to 14
- */
+ /* Set window scaling on max possible window */
space = max_t(u32, space, sysctl_tcp_rmem[2]);
space = max_t(u32, space, sysctl_rmem_max);
space = min_t(u32, space, *window_clamp);
- while (space > 65535 && (*rcv_wscale) < 14) {
+ while (space > U16_MAX && (*rcv_wscale) < TCP_MAX_WSCALE) {
space >>= 1;
(*rcv_wscale)++;
}
@@ -253,7 +251,7 @@ void tcp_select_initial_window(int __space, __u32 mss,
}
/* Set the clamp no higher than max representable value */
- (*window_clamp) = min(65535U << (*rcv_wscale), *window_clamp);
+ (*window_clamp) = min_t(__u32, U16_MAX << (*rcv_wscale), *window_clamp);
}
EXPORT_SYMBOL(tcp_select_initial_window);
--
1.9.1
